Electronic device, data communication method and data processing method for electronic device

ABSTRACT

When an interruption of a bus reset occurs in accordance with the IEEE1394 standard at the time of turn-on of a power source or the like, whether a loop connection has been made or not is discriminated. If it is determined that the loop connection has been made, “i.LINK NG” or “i.LINK LOOP” as a warning display showing that the loop connection has been made is displayed. By displaying such a warning, the user or the like can recognize the fact that the loop connection has been made. A measure for cancelling the loop connection can be performed. If it is determined that the loop connection is not performed, such a warning display is not performed but the ordinary operation according to the IEEE1394 standard is performed.

TECHNICAL FIELD

The invention relates to an electronic apparatus, a data communicatingmethod, and a data processing method for an electronic apparatus. Moreparticularly, the invention relates to an electronic apparatus, a datacommunicating method, and a data processing method for an electronicapparatus, in which transmission and reception of data are performedthrough a digital communication bus.

BACKGROUND ART

In recent years, as an interface for multimedia data transfer, IEEE (TheInstitute of Electronical and Electrical Engineers) 1394, HighPerformance Serial Bus, for realizing a high speed data transfer and areal-time transfer has been standardized.

According to the IEEE1394 standard, for example, a plurality (up to 63)of application side circuits such as MPEG (Moving Picture Expert Group)transporters or the like can be connected to the IEEE1394 serial bus. Aconnecting format of the IEEE1394 serial bus has been specified so as tohave a node branch, namely, what is called a tree shape. A circuitserving as a branch point, namely, a node of the tree-shaped connectingformat is a physical layer circuit in each IEEE1394 serial interface.

According to the IEEE1394 standard, the insertion or ejection of a buscable to/from a port can be performed in a hot state, namely, in a statewhere a power source is turned on and an apparatus is operating. A busreset is generated at a point when the node is added or deleted by theinsertion or ejection of the bus cable to/from the port and aparent/child relation between the nodes is determined.

In the case where the cable is connected in a loop shape such as a casewhere the user erroneously connects or the like, the parent/childrelation cannot be determined and the data cannot be transferred.

It will be, therefore, convenience if there is a function such that inthe case where the cable is connected in a loop shape, the user isnotified of such a fact through a display unit of each electronicapparatus as an application side circuit. However, an electronicapparatus having such a function does not exist yet.

DISCLOSURE OF INVENTION

It is, therefore, an object of the invention to provide an electronicapparatus having such a function that in the case where a cable isconnected in a loop shape, the user is notified of such a fact through adisplay unit of each electronic apparatus as an application side circuitand to provide a data communicating method and a data processing methodfor such an electronic apparatus.

To solve the above problem, according to the invention, there isprovided an electronic apparatus which is connected to another apparatusby a digital communication bus and performs transmission and receptionof data via the digital communication bus, comprising: a display unit;and a control unit for controlling the operation of the display unit,wherein the control unit detects whether another apparatus and thedigital communication bus are connected so as to form a loop or not, andwhen a detection result indicates that they are connected so as to formthe loop, the display unit is allowed to perform a warning display.

According to the invention, there is provided a data communicatingmethod of connecting a plurality of electronic apparatuses by a digitalcommunication bus and performing transmission and reception of data viathe digital communication bus, comprising the steps of: detectingwhether another electronic apparatus of the plurality of electronicapparatuses and the digital communication bus are connected so as toform a loop or not in at least one of the plurality of electronicapparatuses; and when it is detected that the digital communication busis connected to another apparatus so as to form the loop, performing awarning display.

According to the invention, there is provided an electronic apparatuswhich is connected to another apparatus by a digital communication busand performs transmission and reception of data via the digitalcommunication bus, comprising a control unit for controlling theoperation of the apparatus, wherein the control unit detects whetheranother apparatus and the digital communication bus are connected so asto form a loop or not and generates a control signal for performing awarning display when a detection result indicates that they areconnected so as to form the loop.

According to the invention, there is provided a data processing methodfor an electronic apparatus which is connected to another apparatus by adigital communication bus and performs transmission and reception ofdata via the digital communication bus, wherein a control unit detectswhether another apparatus and the digital communication bus areconnected so as to form a loop or not and generates a control signal forperforming a warning display when a detection result indicates that theyare connected so as to form the loop.

As mentioned above, according to the invention, the control unit detectswhether another apparatus and the digital communication bus areconnected so as to form the loop or not and generates the control signalfor performing a warning display when a detection result indicates thatthey are connected so as to form the loop. Therefore, for example, thefact that a cable of a bus such as an IEEE1394 serial bus or the likehas been connected in a loop shape can be accurately displayed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing an example of a fundamentalconstruction of an isochronous communication system circuit in anIEEE1394 serial interface bus;

FIG. 2 is a block diagram showing an example of a construction of asystem in which a plurality of electronic apparatuses are connected byusing the IEEE1394 serial interface bus;

FIG. 3 is a block diagram showing a specific example of the system inwhich a plurality of electronic apparatuses are connected by using theIEEE1394 serial interface bus;

FIG. 4 is a block diagram for explaining the case where nodes areconnected so as to form a loop;

FIG. 5 is a schematic diagram showing an example of a display accordingto the invention;

FIG. 6 is a schematic diagram showing another example of a displayaccording to the invention; and

FIG. 7 is a flowchart for explaining processes in an embodiment of theinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

Prior to describing an embodiment of the invention, the IEEE1394standard will be first explained for easy understanding. As a datatransfer via the IEEE1394 interface, there are a conventionalasynchronous transfer for performing a request and a receptionconfirmation such as Request and Acknowledge and an isochronous transferin which data is certainly transmitted from a certain node once every125 μsec. In the IEEE1394 interface, the data transfer is performed on apacket unit basis. In the IEEE1394 interface, a unit of minimum data tobe handled is one quadlet (=4 bytes=32 bits).

Such an IEEE1394 serial interface for performing the transmission andreception of a packet will be described with reference to FIG. 1. Asignal processing circuit 10 of the IEEE1394 serial interface(hereinafter, referred to as a signal processing circuit 10) has: aphysical layer circuit 11 for directly driving an IEEE1394 serial bus;and a link layer circuit 12 for controlling a data transfer of thephysical layer circuit 1. The physical layer circuit 11 is connected toa serial interface bus BS through a port. For example, an applicationside circuit 13 such as an MPEG transporter or the like is connected tothe link layer circuit 12.

In the IEEE1394 standard, it is assumed that up to 63 signal processingcircuits 10 can be connected through the serial interface bus BS. Aconnecting format of the serial interface bus BS has been specified soas to have a node branch, namely, what is called a tree shape. A circuitserving as a branch point, namely, a node of the tree-shaped connectingformat is the physical layer circuit 11 in the signal processing circuit10. One or a plurality of ports can be provided for the physical layercircuit 11. The serial interface bus BS is connected to each of theports.

According to the IEEE1394 standard, the insertion or ejection of a buscable to/from the port can be performed in a hot state, namely, in astate where a power source is turned on and each electronic apparatus aseach application side circuit 13 is operating. A bus reset is generatedat a point when the node is added or deleted by the insertion orejection of the bus cable to/from the port and a parent/child relationbetween the nodes is determined.

FIG. 2 shows an example of a system in which three nodes are connectedin a tree shape by using the IEEE1394 serial bus cable. The cable of theIEEE1394 serial bus is shown by a bold line. Such a system 20 has nodes21, 22, and 23 as physical layer circuits constructing the signalprocesses of the IEEE1394 serial interface. Two ports p1 and p2 areprovided for each of the nodes 21, 22, and 23. Each of the nodes 21, 22,and 23 has a register showing an operating mode of the node and aregister showing an operating mode of each port. In this example, theport p2 of the node 22 is connected to the port p1 of the node 21 andthe port p1 of the node 23 is connected to the port p2 of the node 21.

The node 21 recognizes the fact that the nodes 22 and 23 are the childnodes in response to requests from the nodes 22 and 23 and, thereafter,transmits a signal “TX_(—)CHILD_(—)NOTIFY” to the nodes 22 and 23. Thus,a connecting relation such that the node 21 is a parent and the nodes 22and 23 are children is satisfied. In dependence on a connection timingof the bus cable, there is also a case where the node 21 transmits arequest signal “TX_(—)PARENT_(—)NOTIFY” to the node 22 or 23 and thenode 22 or 23 becomes the parent node.

However, when considering a case where the port p1 of the node 22 andthe port p2 of the node 23 are further connected in the constructionshown in FIG. 2, in this case, the nodes 21, 22, and 23 transmit therequest signal “TX_(—)PARENT_(—)NOTIFY”. Thus, the parent/child relationcannot be determined among the nodes 21, 22, and 23 and the transmissionand reception of the packet are impossible. As mentioned above, if apart of the system shown in FIG. 2 is connected in a loop shape by theloop connection, namely, by connecting a certain node and anothercertain node by the cable of the IEEE1394 serial bus, the transmissionand reception of the packet are impossible. The operation according tothe IEEE1394 standard cannot be performed.

An embodiment of the invention will now be described hereinbelow. FIG. 3shows a specific example of the system in which a plurality ofelectronic apparatuses are connected by using the IEEE1394 serial bus.In this example, a digital satellite receiver 31 a, an optical discrecording and/or reproducing apparatus (hereinafter, simply referred toas an optical disc drive apparatus) 32, and a DV (Digital Video) deck 33a are connected by the IEEE1394 serial bus. The cable of the IEEE1394serial bus is shown by a bold line.

The optical disc drive apparatus 32 records/reproduces data such asaudio data or the like by using a recordable magnetooptic disk or a readonly optical disc. The optical disc drive apparatus 32 has, for example,an I/O unit 32 d, a controller 32 c, an operating unit 32 b, arecording/reproducing unit 32 e, and a display unit 41. The controller32 c comprises a microprocessor, a memory, or the like and controls thewhole optical disc drive apparatus 32 in accordance with a program whichhas previously been stored in the memory. The I/O unit 32 d is aninterface corresponding to the IEEE1394 serial bus. The transmission andreception of the data between the optical disc drive apparatus 32 and anexternal apparatus via the IEEE1394 serial bus are performed via the I/Ounit 32 d on the basis of a control of the controller 32 c. A pluralityof IEEE1394 serial buses can be connected to the I/O unit 32 d.

The operating unit 32 b has one or a plurality of switching devices,dial devices, and the like. When a predetermined operation is performedto the switching devices, dial devices, or the like by the user, theoperating unit 32 b generates a control signal based on the operation.The control signal is supplied to the controller 32 c. The display unit41 comprises, for example, an LCD (Liquid Crystal Display) and itsdisplay is controlled by a display control signal which is supplied fromthe controller 32 c.

The recording/reproducing unit 32 e comprises: a driving unit foractually performing the recording of data to a recordable magnetoopticdisk or the reproduction of data from a recordable magnetooptic disk ora read only optical disc; and a data processing unit for performing dataprocesses necessary for recording or reproduction. On the basis of thecontrol of the controller 32 c, the recording/reproducing unit 32 eperforms the recording of data to the recordable magnetooptic disk orthe reproduction of data from the recordable magnetooptic disk or readonly optical disc.

For example, the audio data inputted from the outside to the I/O unit 32d is supplied to the recording/reproducing unit 32 e via the controller32 c. The audio data is recorded onto the recordable magnetooptic diskloaded in a predetermined place of the recording/reproducing unit 32 eby the control of the controller 32 c in accordance with the operationby the user to the operating unit 32 b. The audio data is reproducedfrom, for example, the read only optical disc loaded in thepredetermined place of the recording/reproducing unit 32 e. Thereproduced audio data is supplied to the I/O unit 32 d through thecontroller 32 c and outputted to the outside.

For example, as shown in FIG. 5, the optical disc drive apparatus 32has: an inserting/ejecting port 32 a for inserting or ejecting a discinto/from an operation panel on the front side of the apparatus 32; aplurality of operating switches 32 b for switching the operation of theapparatus 32; and the display unit 41. The DV deck 33 a records orreproduces a digital video signal to/from a video tape. As for each ofthe digital satellite receiver 31 a, optical disc drive apparatus 32,and DV deck 33 a, as a connector for connecting a connecting cable forIEEE1394, a plurality of ports are provided in a lower portion or thelike on the rear side or front side of each apparatus. Monitors 31 b and33 b are connected to the digital satellite receiver 31 a and DV deck 33a in order to display at least a reproduced video signal, respectively.

FIG. 4 shows a case where the optical disc drive apparatus 32 and DVdeck 33 a are further connected by using an IEEE1394 serial interfacebus 103 in the system construction shown in FIG. 3. In this case, sincethe connecting cable for IEEE1394 is loop connected as shown in thediagram, as mentioned above, the parent/child relation based on“TX_(—)PARENT_(—)NOTIFY” cannot be determined among the digitalsatellite receiver 31 a, optical disc drive apparatus 32, and DV deck 33a, the tree structure cannot be decided, and a nodeID cannot benumbered. Therefore, a function as a bus cannot be performed, forexample, packet transmission and reception between desired electronicapparatuses cannot be performed, and the like. In this case, a normalfunction cannot be expected so long as a connection change to cancel thephysical loop connection is not performed by the user or the like.

In many cases, it is actually difficult to recognize the fact that aplurality of electronic apparatuses are connected in a loop shape by theconnecting cable for IEEE1394 by confirming the physical connectionitself, namely, by confirming which apparatuses are erroneously wired orconnected. Therefore, it will be convenient if there is a function fordisplaying the fact that they are loop connected to the user or thelike. In case of the electronic apparatuses such that the information isoutputted to the user through displays each having a relatively largedisplay area such as monitors 31 b and 33 b or the like connected to thedigital satellite receiver 31 a and DV deck 33 a in FIG. 4, it issufficient to display that the cable connects the apparatuses so as toform a loop, for example, to display characters such as “Cable is loopconnected” or the like through the monitors.

However, in a small electronic apparatus for consumers, a display areaof a display unit is often small. In such an electronic apparatus, it isdifficult to display a warning of a long sentence by using the monitoras mentioned above. In the invention, therefore, when it is detectedthat the bus (cable) connects the apparatuses so as to form a loop, asimple display consisting of the small number of characters using akeyword such as “i.LINK NG”, i.LINK LOOP”, “CABLE LOOP”, or the like isperformed in the display unit. As mentioned above, “i.LINK” is atrademark showing the IEEE1394 serial bus.

FIG. 5 shows an example of a specific display. “i.LINK NG” is displayedas a warning display in the case where, the cable connects theapparatuses to, for example, the display unit 41 comprising an LCD orthe like provided for an operation panel of the optical disc driveapparatus 32 so as to form a loop as shown in, for example, FIG. 4. FIG.6 shows another example of a warning display which is displayed in thedisplay unit 41. In the example shown in FIG. 6, “i.LINK LOOP” isdisplayed in the case where the cable is loop connected to, for example,the display unit 41 provided for the operation panel of the optical discdrive apparatus 32.

“i.LINK LOOP” has the larger number of characters than that of “i.LINKNG” and shows more detailed information. Therefore, it is considered tobe preferable to display a warning “i.LINK NG” when the display area ofthe display unit provided for the electronic apparatus is small and todisplay a warning “i.LINK LOOP” if there is a surplus display area ofthe display unit.

Since the warning as mentioned above is displayed in the display unit ofthe electronic apparatus, the user or the like recognizes that theapparatuses, namely, the nodes are connected so as to form a loop, and ameasure for cancelling the loop such that the connecting cable 103 inFIG. 4 is disconnected and the connection is returned to the state shownin FIG. 3, a connecting cable 101 or 102 is disconnected, or the like isperformed by the user or the like, so that the normal operationaccording to the IEEE1394 standard is performed, and communicationbetween the electronic apparatuses in the system is enabled.

When the optical disc drive apparatus 32 detects that the loopconnection is cancelled as mentioned above, the warning display as shownin FIG. 5 or 6 is deleted from the display unit 41. Thus, the user orthe like is notified of the fact that the state where the apparatusesare connected so as to form a loop has been cancelled.

Processes regarding the display in the case where the fact that theapparatuses, namely, the nodes have been connected so as to form a loopis detected in the optical disc drive apparatus 32 will be describedwith reference to FIG. 7. The processes in the flowchart of FIG. 7 areexecuted in the controller 32 c mentioned above. In step S1, aninterruption of a bus reset occurs in accordance with the IEEE1394standard when the power source is turned on, when a new node isconnected to the bus, or the like. After the bus reset, usually, theprocess such as setting of the parent/child relation between the nodesin the system based on “TX_(—)PARENT_(—)NOTIFY” or the like is executedas mentioned above. In the embodiment of the invention, the processingroutine advances to step S2 subsequently to step S1.

In step S2, the controller 32 c of the optical disc drive apparatus 32detects whether the process which is executed after the bus reset suchas setting of the parent/child relation between the nodes based on, forexample, “TX_(—)PARENT_(—)NOTIFY” mentioned above or the like has beenfinished within a predetermined time or not, thereby discriminatingwhether the nodes have been connected so as to form a loop or not.

If it is determined that the nodes are connected so as to form a loop,step S3 follows. In the other case, step S4 follows. If it is determinedin step S2 that the processes are not finished within the predeterminedtime but the nodes are connected so as to form a loop, a warning of“i.LINK NG” or “i.LINK LOOP” is displayed in the display unit 41 inresponse to the control signal from the controller 32 c of the apparatus32 in step S3.

That is, if it is determined in step S2 that the processes are notfinished within the predetermined time but the nodes are formed so as toform a loop, the display control signal to perform the warning displayas mentioned above is generated by the controller 32 c. The displaycontrol signal is supplied to the display unit 41 and the warning asshown in FIG. 5 or 6 mentioned above is displayed in the display unit 41on the basis of the supplied display control signal.

If it is determined in step S2 that the processes which are executedafter the bus reset are finished within the predetermined time but thenodes are not connected so as to form a loop, step S4 follows. Thewarning such as “i.LINK NG”, “i.LINK LOOP”, or the like is not displayedin the display unit 41 but the ordinary operation such as setting of theparent/child relation between the nodes or the like according to theIEEE1394 standard is performed.

The foregoing embodiment of the invention has been described by usingthe optical disc drive apparatus 32 as an example of the electronicapparatus in which the display area of the display unit is small or anenough display area cannot be assured. On the other hand, the inventioncan be also applied to an electronic apparatus which is connected to,for example, the digital satellite receiver 31 a, DV deck 33 a, or thelike in FIG. 2 and uses a relatively large monitor for the optical discdrive apparatus 32.

Besides the case of performing the foregoing warning display to thedisplay unit of a small display area provided for the operation panel orthe like of one of the plurality of electronic apparatuses constructingthe system of FIG. 2, for example, if the foregoing warning display isperformed to each of the display units of the plurality or all of theelectronic apparatuses constructing the system, the user or the like canmore easily and certainly recognize the loop connection.

The embodiment of the invention mentioned above is obtained by applyingthe invention to the system in which a plurality of electronicapparatuses are connected by the IEEE1394 serial bus. On the other hand,the invention can be applied also to a system using another kind of bus.It is necessary to use a display character train according to the kindof bus.

The invention is not limited to the embodiment of the inventionmentioned above but many modifications and variations are possiblewithin the scope of the invention without departing from the spiritthereof.

1. An electronic apparatus which is connected to another apparatus viaan IEEE 1394 bus and performs transmission and reception of data throughsaid IEEE 1394 bus, comprising: a display unit; and a control unit forcontrolling the operation of said display unit, wherein said controlunit detects whether said another apparatus and said digitalcommunication bus are connected so as to form a loop or not, and when aresult of said detection indicates that they are connected so as to formsaid loop, said control unit controls said display unit to display awarning message related to said loop connection, and said control unitdetects whether they are connected so as to form the loop or not bydiscriminating whether processes which are executed after a bus resetwas generated have been finished within a predetermined period or not.2. The electronic apparatus according to claim 1, wherein each apparatusincludes at least two bus ports.
 3. The electronic apparatus accordingto claim 2, wherein when the processes which are executed after the busreset was generated are not finished within the predetermined period,said control unit detects that they are connected so as to form saidloop and controls said display unit to display said warning message. 4.The electronic apparatus according to claim 2, wherein when theprocesses which are executed after the bus reset was generated arefinished within the predetermined period, said control unit detects thatthey are not connected so as to form said loop and does not control saiddisplay unit to display said display message.
 5. A data communicatingmethod whereby a plurality of electronic apparatuses are connected via aIEEE 1394 bus and transmission and reception of data are performedthrough said IEEE 1394 bus, comprising the steps of: detecting whetheranother apparatus among said plurality of electronic apparatuses andsaid digital communication bus are connected so as to form a loop or notwith at least one of said plurality of electronic apparatuses; when itis detected that said digital communication bus is connected to saidanother apparatus so as to form said loop, controlling a display unit todisplay a warning message related to said loop connection; and detectingwhether they are connected so as to form the loop or not bydiscriminating whether processes which are executed after a bus resetwas generated have been finished within a predetermined period or not.6. The data communicating method according to claim 5, wherein each ofsaid plurality of apparatuses includes at least two bus ports.
 7. Thedata communicating method according to claim 6, wherein when theprocesses which are executed after the bus reset was generated are notfinished within the predetermined period, it is detected that they areconnected so as to form said loop and said display unit is controlled todisplay said warning message.
 8. The data communicating method accordingto claim 6, wherein when the processes which are executed after the busreset was generated are finished within the predetermined period, it isdetected that they are not connected so as to form said loop and saiddisplay unit is controlled to not display said warning message.